Heat exchanger

ABSTRACT

A heat exchanger provided with tubes ( 2 ) for flowing a medium and tanks ( 4 ), performs heat exchange of the medium by heat conducted to the tubes, has the tubes and the tanks assembled to form a heat exchanger core ( 1 ), and has the heat exchanger core brazed into one body, wherein the tubes ( 2 ) are formed by shaping a plate-shaped material ( 200 ), have beads ( 202 ) which are formed by bending the material, and have a sacrifice layer ( 210 ) disposed on the outer surfaces of the tubes; the heat exchanger core ( 1 ), excluding at least the tubes, is provided with a brazing material which fills recessed portions ( 203 ) on the outer surfaces of the tubes which are formed when the beads are formed; and the brazing material (R) which melts from the heat exchanger core at the time of integral brazing fills the recessed portions on the outer surfaces of the tubes. The brazing material (R) is formed to melts from the tanks, melts from fins which are separately disposed with the brazing material, or melts from a replaced brazing material which is disposed on the heat exchanger core.

TECHNICAL FIELD

[0001] The present invention relates to a heat exchanger which isprovided with tubes for flowing a medium and exchanges heat of themedium with heat conducted to the tubes.

BACKGROUND ART

[0002] Generally, a heat exchanger such as a condenser, an evaporator, aradiator, a heater core or the like mounted on automobiles is providedwith tubes for flowing a medium, fins fitted to the tubes and tankswhich are connected to the tube ends and configured to perform the heatexchange of the medium with heat conducted to the tubes and the fins.

[0003] And, this type of heat exchanger is produced by assembling thetubes, fins and tanks which are made of aluminum or an aluminum alloyand heating the assembly in a furnace to be brazed into one body. Abrazing material and flux necessary for the brazing are previouslyapplied to necessary portions of the respective members before heating.

[0004] As the tubes for the heat exchanger, those produced by shaping aplate-shaped material are known. And, these tubes are provided withbeads which are shaped by bending a material, and the beads serve toimprove a heat-exchange property and a pressure resistance of the tubes.

[0005] Besides, this heat exchanger has a sacrifice layer disposed onthe outer surfaces of the tubes, so that the corrosion resistance of thetubes can be improved.

[0006] For example, the sacrifice layer which is formed of an Al—Znbased alloy is disposed on the core material of the tubes made of anAl—Mn based alloy, and electric potential of the tube core materialbecomes high with respect to the sacrifice layer. As a result, thecorrosion resistance of the tubes is improved by a sacrificial anodeeffect.

[0007] When the tubes made of the plate-shaped material as describedabove are provided with beads, recessed portions are formed on the outersurfaces depending on the beads.

[0008] These recessed portions on the outer surfaces of the tubes makeit difficult to connect the tubes and the tanks and the recessedportions readily gather dust and water, thus,they become a cause ofadvancing the corrosion of the tubes.

[0009] Especially, as described in Japanese Patent Laid-Open PublicationNo. HEI 4-20791, there are tubes in which the mutually opposed surfacesof the material at the beads are put together to eliminate the recessedportions of the outer surfaces. But, in practice, it is very hard tocompletely eliminate the recessed portions, and these tubes mostly havesome recessed portions remaining on the outer surfaces.

[0010] When a brazing material is clad to the surface of the materialwhich becomes the outer surface of the tube, the brazing material meltedby heating accumulates in the recessed portions, so that the recessedportions can be filled with the brazing material. But, when the brazingmaterial for filling the recessed portions is separately disposed on thetubes, there is a disadvantages that the production cost becomes veryhigh.

[0011] Accordingly, in view of the above problem, it is an object of thepresent invention to provide a heat exchanger which can efficientlysecure the corrosion resistance of the tubes and can be produced at alow cost.

DISCLOSURE OF THE INVENTION

[0012] The present invention is a heat exchanger which is provided withtubes for flowing a medium and tanks to which ends of the tubes areconnected, performs heat exchange of the medium by heat conducted to thetubes, has the tubes and the tanks assembled to form a heat exchangercore, and has the heat exchanger core brazed into one body, wherein thetubes are formed by shaping a plate-shaped material, have beads whichare formed by bending the material, and have a sacrifice layer disposedon the outer surfaces of the tubes; the heat exchanger core, excludingat least the tubes, is provided with a brazing material for fillingrecessed portions on the outer surfaces of the tubes which are formedwhen the beads are formed; and the recessed portions on the outersurfaces of the tubes are filled with the brazing material which meltsfrom the heat exchanger core at the time of integral brazing.

[0013] By configuring as described above, the corrosion resistance ofthe tubes is efficiently secured. Specifically, the recessed portions onthe outer surfaces of the tubes tend to gather dust and water and becomea cause of promoting corrosion of the tubes. But, the present inventionprovides the sacrifice layer on the outer surfaces of the tubes andrecessed portions are filled with the brazing material, which melts fromthe heat exchanger core, into the recessed portions. Thus, the corrosionresistance of the tubes is improved securely. When the brazing materialfor filling the recessed portions is provided on the tubes, theproduction cost becomes very high. Therefore, the brazing material forfilling the recessed portions is disposed on the heat exchanger coreother than the tubes to save the cost.

[0014] The brazing material to be used may be in a form such as clad onthe tanks, disposed on the fins, a replaced brazing material disposed onthe heat exchanger core, or the like.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a front view showing a heat exchanger according to anembodiment of the present invention;

[0016]FIG. 2 is a perspective view showing tubes, fins and a tankaccording to the embodiment of the invention;

[0017]FIG. 3 is a sectional diagram showing a tube according to theembodiment of the invention;

[0018]FIG. 4 is a sectional diagram showing a tube according to anembodiment of the invention;

[0019]FIG. 5 is a top view showing a tube and a tank according to theembodiment of the invention; and

[0020]FIG. 6 is a side view showing a tube and fins according to anembodiment of the invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0021] Embodiments of the present invention will be described in detailwith reference to the accompanying drawings.

[0022] As shown in FIG. 1 and FIG. 2, a heat exchanger of thisembodiment is a condenser of a refrigerating cycle for an in-car airconditioner mounted on automobiles, and has a heat exchanger core 1configured by alternately stacking a plurality of tubes 2 and aplurality of fins 3 and connecting both ends of the tubes 2 to a pair oftanks 4.

[0023] The tanks 4 of this embodiment are cylindrical members which areprovided with an inlet joint 401 and an outlet joint 402 for connectingan external pipe and holes 403 into which the ends of the tubes 2 areinserted for connection, and have their inside portioned at a prescribedwidth.

[0024] A medium is taken-in through the inlet joint 401, passing throughthe tubes 2 while heat exchanging with heat conducted to the tubes 2 andthe fins 3 and discharged through the outlet joint 402.

[0025] And, side plates 5, which are reinforcing members, arerespectively disposed on the top and bottom of a layer of the tubes 2and the fins 3. Both ends of the side plates 5 are supported by thetanks 4.

[0026] The tubes 2, the fins 3, the tanks 4 and the side plates 5 areassembled by a jig, and heated in a furnace to be brazed into one body.A brazing material and flux are previously disposed at necessaryportions of these members.

[0027] As shown in FIG. 3, the tubes 2 of this embodiment have a flatshape formed by rolling a plate-shaped material 200 made of an aluminumalloy so to have a joined portion 201 which is formed by connecting theends in a breadth direction of the material 200 and a plurality of beads202 which are formed by bending the material 200 inwardly, and thejoined portion 201, the tops of the beads 202 and the inner opposedportions are brazed. And, a sacrifice layer 210 is disposed on thesurface of the material 200 which will become the outer surfaces of thetubes 2.

[0028] The beads 202 improve the heat-exchange property and pressureresistance of the tubes 2, and the sacrifice layer 210 improves thecorrosion resistance of the tubes 2.

[0029] The beads 202 may be formed to braze the opposed tops mutually asshown in FIG. 4.

[0030] Besides, a brazing material R fills the recessed portions 203 onthe outer surfaces of the tubes 2 formed according to the beads 202.

[0031] The brazing material R to fill the recessed portions 203 meltsfrom the fins 3 and the tanks 4 at the time of brazing and enters intothe recessed portions 203 as shown in FIG. 5 and FIG. 6.

[0032] Specifically, the brazing material is clad to or disposed on thefins 3, and the tubes 2 have the tops of the fins 3 brazed by brazingand the brazing material R melting from the fins 3 enters into therecessed portions 203.

[0033] Here, the replaced brazing material may be disposed between thetubes 2 and the fins 3 or between the tubes 2 and the tanks 4.

[0034] Thus, the entry of dust and water into the recessed portions 203can be prevented by filling the recessed portions 203 with the brazingmaterial R, and the corrosion resistance of the tubes 2 can be improved.And, the tubes 2 can be reinforced by the brazing material R, and thepressure resistance and strength of the tubes 2 can also be improved.

[0035] In this embodiment, it is configured to fill all the recessedportions 203 on the outer surfaces of the tubes 2 with the brazingmaterial R, but the brazing material R may partly fill around the topsof the fins 3, around the holes 403 of the tanks 4, or the like.

[0036] The replaced brazing material may be disposed as the brazingmaterial on the outer surface of the tubes 2 to fill the recessedportions 203 with the brazing material. Specifically, it may beconfigured to fill the recessed portions 203 with the replaced brazingmaterial disposed on the tubes 2 in additon to the brazing materialmelting from the fins 3 and the tanks 4.

[0037] In the heat exchanger of this embodiment as described above, thetubes are formed by shaping the plate-shaped material and have the beadswhich are formed by bending the material, the sacrifice layer isdisposed on the outer surfaces, and the brazing material which meltsfrom the fins and the tanks at the time of brazing fills the recessedportions on the outer surfaces of the tubes which are formed accordingto the beads. Thus, the corrosion resistance of the tubes can be securedefficiently.

[0038] In other words, the recessed portions on the outer surface of thetubes tend to gather dust and water and become a cause of promoting thecorrosion of the tubes. But, the present invention disposes thesacrifice layer on the outer surfaces of the tubes and the brazingmaterial, which melts from the tanks and the fins, enters into and fillsthe recessed portions, so that the corrosion resistance of the tubes canbe improved without fail.

[0039] And, the tubes of this embodiment are formed by shaping theplate-shaped material and have the beads which are formed by bending thematerial, and the sacrifice layer is disposed on the outer surfaces ofthe tubes. The heat exchanger is configured by disposing the replacedbrazing material on the tubes at the time of brazing and the brazingmaterial of the replaced brazing material fills the recessed portions onthe outer surfaces of the tubes which are formed according to the beads.This configuration secures the corrosion resistance of the tubesefficiently.

[0040] In other words, the corrosion resistance of the tubes can beimproved without fail by filling the recessed portions with the brazingmaterial of the replaced brazing material disposed on the tubes.

[0041] In the specific examples shown in the drawings, the tubes 2 andthe plurality of fins 3 are alternately stacked, and both ends of thetubes are respectively connected to the pair of tanks 4 to configure theheat exchanger core 1. But, the present invention is not limited to itand can also be applied to, for example, a heat exchanger core not usingfins and a heat exchanger core of another embodiment.

[0042] Industrial Applicability

[0043] The present invention is a heat exchanger which can have thecorrosion resistance of the tubes secured efficiently and can besuitably used as a heat exchanger for a condenser, an evaporator, aradiator, a heater core and the like mounted on automobiles.

1. A heat exchanger which is provided with tubes for flowing a mediumand tanks to which ends of the tubes are connected, performs heatexchange of the medium by heat conducted to the tubes, has the tubes andthe tanks assembled to form a heat exchanger core, and has the heatexchanger core brazed into one body, wherein: the tubes are formed byshaping a plate-shaped material, have beads which are formed by bendingthe material, and have a sacrifice layer disposed on the outer surfacesof the tubes; the heat exchanger core, excluding at least the tubes, isprovided with a brazing material which fills recessed portions on theouter surfaces of the tubes which are formed when the beads are formed;and the brazing material which melts from the heat exchanger core at thetime of integral brazing fills the recessed portions on the outersurfaces of the tubes.
 2. The heat exchanger according to claim 1,wherein the brazing material melting from the tanks at the time ofintegral brazing fills the recessed portions on the outer surfaces ofthe tubes.
 3. The heat exchanger according to claim 1, wherein the finshaving the brazing material is fitted to the heat exchanger core, andthe brazing material melting from the fins at the time of integralbrazing fills the recessed portions on the outer surfaces of the tubes.4. The heat exchanger according to claim 1, wherein a replaced brazingmaterial is disposed on the heat exchanger core, and the brazingmaterial melting from the replaced brazing material at the time ofintegral brazing fills the recessed portions on the outer surfaces ofthe tubes.
 5. The heat exchanger according to claim 4, wherein thereplaced brazing material is disposed on any one of the tubes, the finsand the tanks or two or more of them.